What decideds how much bodyguards your general has

[Skoran]

A simple question but after years of RTW and EB I still dont know it, lol :p

And is their a way to increase the number of bodyguards?

[johnhughthom]

I think influence helps, being Faction leader or heir seems to raise it too.

[Aemilius Paulus]

Personal Security, age and Influence all increase the size of general's bodyguard. Also, a faction leader and heir have increased bodyguard sizes. The influence one doesn't always work though. Increasing Personal Security and having the general get older are the best ways to increase his bodyguard as I have found out from my personal experience.

EDIT: johnhughthom beat me to the first post, but I just found a thread in Ludus Magna about this: https://forums.totalwar.org/vb/showthread.php?t=47146 - it pretty much says the same things that i have already mentioned in my post.

Ludus Magna forum is the most useful RTW forum, with tons of valid research being done there on all of the game mechanics.